This invention relates broadly to a method and apparatus for analyzing gaseous mixtures and, more specifically, to the measurement of small concentrations of vinyl chloride in air.
Concern with the health hazards associated with industrial exposure to vinyl chloride has caused the allowable concentration of vinyl chloride to be reduced substantially from the previous standard of five hundred parts per million for continuous exposure. Analysis of vinyl chloride in industrial atmospheres at low levels approaching zero concentration has become of considerable interest. The present invention is directed primarily to a new method and apparatus for making such analyses of low concentrations of vinyl chloride in air. More broadly, the invention may be applied to analysis of other compounds as well.
Available methods for measurement of vinyl chloride in air include gas chromatography and infrared spectrometry, which are complex and quite expensive, although very sensitive to low concentrations. Other possible techniques include thermal decomposition of the compound, an example of which is given in U.S. Pat. No. 3,546,079. Simple leak detection tests in which flames are colored by the compound detected have also been applied for the relatively high concentration heretofore common, but these are not suitable for the low concentrations which are currently of interest. Thus, the present invention has as an objective providing a new, relatively simple, and inexpensive method for analysis of low concentrations of vinyl chloride in air.